Ever since the discovery of the quark, high-energy
lepton scattering experiments have provided increasingly
more accurate data on
the structure of neutrons and protons (nucleons).
Our present knowledge is extensive but incomplete. One of
the currently interesting topics of research
focuses on how the quark-antiquark sea, and the
gluons that mediate the strong interaction, influence nucleon
and nuclear structure.
I am presently involved in experiments
designed to understand this.
Several experiments have been done over the past
decade at the Stanford Linear Accelerator Center, including
E143,
E154, and
E155,
which have measured polarized deep-inelastic scattering.
They indicate that the spin of the neutron or proton
does not come predominately from the quarks. A set of follow-up measurements
at SLAC using a polarized beam of high-energy
photons,
E159,
E160, and
E161, has been planned but never executed.
My current research centers on
Jefferson Lab in Newport News, VA (near William
and Mary) and uses the
CLAS (the CEBAF Large Acceptance Spectrometer). Experiments
include BoNuS,
E6 and
EG1.
The Spin Group at William and Mary (Armstrong,
Averett, Carlini, Finn, Griffioen and Lung)
is heavily involved in the
G0 Experiment and the Qweak Experiment
in Hall C at Jefferson Lab,
which study the proton and neutron through parity-violating
electron scattering. Plans are
currently underway to double the energy at
Jefferson Lab, which will allow us to explore the nucleon with much finer detail.